1. Field of the Invention
The invention relates to telecommunications. In particular, the invention relates to providing access bearer related information in a packet data network.
2. Description of the Related Art
Recently also mobile communication networks have started to support transmission of packet switched data or packet data in addition to traditional circuit switched data transmission.
An example of a technique allowing packet data transmission for mobile communication networks is General Packet Radio Service (GPRS). GPRS is designed to support e.g. digital mobile telecommunication networks based on the Global System for Mobile Communications (GSM) standard. However, GPRS is not restricted to only GSM networks but may support for example 3rd Generation Partnership Project (3GPP) based digital mobile telecommunication networks. Other examples of mobile packet data networks are Wireless Local Area Network (WLAN) based mobile communication networks, Code Division Multiple Access (CDMA) based mobile communication networks, Wideband Code Division Multiple Access (WCDMA) based mobile communication networks, Mobile IP (Internet Protocol) based mobile communication networks and Enhanced Data Rates for Global Evolution (EDGE) based mobile communication networks.
A GPRS based mobile communication network comprises supplementary network elements or nodes in addition to existing network elements. These include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). A Serving GPRS Support Node typically delivers packets to and from GPRS enabled terminal devices within its service area. A Gateway GPRS Support Node is typically used as an interface to external IP networks such as the Internet, other mobile service providers' GPRS services, or enterprise intranets.
The introduction of packet data based mobile communication networks has resulted in various value-added subscriber services being provided for these packet data based mobile communication networks. Examples of such subscriber services are packet data based voice, email, content downloading, browsing, streaming and rich calls. Furthermore, packet data based mobile communication networks typically offer network services to support the usage of subscriber services. Such network services include e.g. rerouting, barring, accounting, content proxy services, content blocking services, firewall services, virus scanning services, performance enhancement proxy services, Virtual Private Network (VPN) services, various Quality of Service (QoS) related services and various charging related services for both online and offline charging. Unless otherwise stated, in the following the term ‘service’ is used to refer to both the above value-added subscriber services and the network services supporting them.
A recent trend is to provide the above services by utilizing independent service entities. The term ‘independent’ here refers to the service entities being functionally separate from other network elements. For example, virus scanning services are provided by an independent virus scanning service entity rather than e.g. by a Serving GPRS Support Node or a Gateway GPRS Support Node. Since a service entity is functionally separate from other network elements, it may be implemented as a stand-alone network element physically separate from other network elements. Alternatively, a service entity may be implemented e.g. as a functionally separate software component integrated into a single network element, e.g. into a Gateway GPRS Support Node. Naturally, also several service entities may be integrated into a single physical network element.
The trend of independent service entities necessitates implementation of service processing functions. The service processing functions determine which service or services are to be applied to a given data packet or a traffic flow, and then distribute the data packet or traffic flow to the service entity or entities accordingly. Furthermore, the service processing functions may generate and utilize service rules indicating which service entities and in which order are to be utilized for providing various services. In other words, the service processing functions allow differentiating the distinct service data flows related to various services, so that it is not necessary to have a separate access bearer, e.g. a PDP context, for each service. The service processing functions are able to manage, charge and route these distinct traffic flows, whereas a service entity provides an actual service or services and handles signaling related to the service or services. For example, a home agent of a Mobile IP network, a Traffic Plane Function (TPF) of a 3GPP network, and a Performance Enhancement Proxy (PEP) provide service processing functions.
Typically the service processing functions and the access processing functions have been provided by a single network entity. The term ‘access processing functions’ refers to functions for processing requests to access at least one of the mobile packet data network and external networks the mobile packet data network is connected to. For example, a Gateway GPRS Support Node of a GPRS network and a Packet Data Gateway (PDG) of a WLAN network provide access processing functions.
An even more recent trend, however, is to provide the service processing functions by utilizing one independent network entity and the access processing functions by utilizing another independent network entity. The term ‘independent’ here again refers to the network entities being functionally separate from other network elements. In other words, the service processing functions are provided by a network entity—a service processor—that is functionally separate from the network entity that provides the access processing functions—an access processor. As the access processor and the service processor are functionally separate from each other, they may be implemented as stand-alone network elements physically separate from each other, or they may be implemented e.g. as functionally separate software components integrated into a single physical network element, e.g. into a Gateway GPRS Support Node.
However, the above separation of access processing, service processing and service providing creates problems in certain situations. More specifically, when a data packet is redirected between the independent service entities, the access processor, and the service processor, no information about the PDP (Packet Data Protocol) context of the data packet is conveyed. As is known in the art, the term ‘PDP context’ refers to a set of information describing a wireless session and used in a GPRS network by terminal devices and GPRS Support Nodes for identifying the session. The PDP context comprises information related to e.g. routing, Quality of Service, security and billing. Since no information about the PDP context of the data packet is conveyed between the above independent service entities, access processor and service processor, neither service based Quality of Service nor Quality of Service based charging can be implemented. The IP address of a terminal device is the same in all secondary PDP contexts: therefore without additional identification information about the PDP context, the secondary PDP context of a data packet cannot be known. As a result, service based Quality of Service or Quality of Service based charging cannot be implemented.
Prior art includes application US 2003/0058874 of Sahaya et al., filed Sep. 19, 2002, which is commonly assigned with the present application. The disclosure of this application is incorporated by reference herein. US 2003/0058874 discloses a system and method for providing a Mobile Edge Service in a mobile network.
Therefore, the object of the present invention is to alleviate the problems described above and to introduce a mechanism that allows providing additional identification information about at least the PDP context of a data packet while the data packet is being redirected between the above independent service entities, access processor and service processor.